<?php
/**
 * CSqlDataProvider implements a data provider based on a plain SQL statement.
 *
 * CSqlDataProvider provides data in terms of arrays, each representing a row of query result.
 *
 * Like other data providers, CSqlDataProvider also supports sorting and pagination.
 * It does so by modifying the given {@link sql} statement with "ORDER BY" and "LIMIT"
 * clauses. You may configure the {@link sort} and {@link pagination} properties to
 * customize sorting and pagination behaviors.
 *
 * CSqlDataProvider may be used in the following way:
 * <pre>
 * $count=Yii::app()->db->createCommand('SELECT COUNT(*) FROM tbl_user')->queryScalar();
 * $sql='SELECT * FROM tbl_user';
 * $dataProvider=new CSqlDataProvider($sql, array(
 *     'totalItemCount'=>$count,
 *     'sort'=>array(
 *         'attributes'=>array(
 *              'id', 'username', 'email',
 *         ),
 *     ),
 *     'pagination'=>array(
 *         'pageSize'=>10,
 *     ),
 * ));
 * // $dataProvider->getData() will return a list of arrays.
 * </pre>
 *
 * Note: if you want to use the pagination feature, you must configure the {@link totalItemCount} property
 * to be the total number of rows (without pagination). And if you want to use the sorting feature,
 * you must configure {@link sort} property so that the provider knows which columns can be sorted.
 *
 * @author Qiang Xue <qiang.xue@gmail.com>
 * @version $Id: CSqlDataProvider.php 2820 2011-01-06 17:15:56Z mdomba $
 * @package system.web
 * @since 1.1.4
 */
class CSqlDataProvider extends CDataProvider
{
    /**
     * @var CDbConnection the database connection to be used in the queries.
     * Defaults to null, meaning using Yii::app()->db.
     */
    public $db;
    /**
     * @var string the SQL statement to be used for fetching data rows.
     */
    public $sql;
    /**
     * @var array parameters (name=>value) to be bound to the SQL statement.
     */
    public $params=array();
    /**
     * @var string the name of key field. Defaults to 'id'.
     */
    public $keyField='id';

    /**
     * Constructor.
     * @param string $sql the SQL statement to be used for fetching data rows.
     * @param array $config configuration (name=>value) to be applied as the initial property values of this class.
     */
    public function __construct($sql,$config=array())
    {
        $this->sql=$sql;
        foreach($config as $key=>$value)
        $this->$key=$value;
    }

    /**
     * Fetches the data from the persistent data storage.
     * @return array list of data items
     */
    protected function fetchData()
    {
        $sql=$this->sql;
        $db=$this->db===null ? Yii::app()->db : $this->db;
        $db->active=true;

        if(($sort=$this->getSort())!==false)
        {
            $order=$sort->getOrderBy();
            if(!empty($order))
            {
                if(preg_match('/\s+order\s+by\s+[\w\s,]+$/i',$sql))
                $sql.=', '.$order;
                else
                $sql.=' ORDER BY '.$order;
            }
        }

        if(($pagination=$this->getPagination())!==false)
        {
            $pagination->setItemCount($this->getTotalItemCount());
            $limit=$pagination->getLimit();
            $offset=$pagination->getOffset();
            $sql=$db->getCommandBuilder()->applyLimit($sql,$limit,$offset);
        }

        $command=$db->createCommand($sql);
        foreach($this->params as $name=>$value)
        $command->bindValue($name,$value);

        return $command->queryAll();
    }

    /**
     * Fetches the data item keys from the persistent data storage.
     * @return array list of data item keys.
     */
    protected function fetchKeys()
    {
        $keys=array();
        foreach($this->getData() as $i=>$data)
        $keys[$i]=$data[$this->keyField];
        return $keys;
    }

    /**
     * Calculates the total number of data items.
     * This method is invoked when {@link getTotalItemCount()} is invoked
     * and {@link totalItemCount} is not set previously.
     * The default implementation simply returns 0.
     * You may override this method to return accurate total number of data items.
     * @return integer the total number of data items.
     */
    protected function calculateTotalItemCount()
    {
        return 0;
    }
}
